As far as evolution goes...I've got a few questions about the fossil record and speciation.
1. The four known mechanisms of natural change : Natural selection, mutations, gene exchange, and epigenetics all require long periods -very long periods - of time to produce change.
All but genetic mutations generate relatively small step changes. But the vast majority of mutations are supposedly neutral. They cause neither harm nor benefit. Of those that are nonneutral, it has been calculated that harmful mutations outnumber beneficial mutations by a factor of 10,000 to 1, sometimes 10,000,000 to one.
This explains why ecologists observe far far more extinction events than speciation events in field studies.
All these processes require long...very long periods to produce significant changes. But those changes also require a stable or gradually changing environment to be beneficial. Catastrophic or rapid changes in the environment would negate these changes or cause extinction outright.
Now we all know that earths environment, while it can seem pretty stable to us in our short lifespans, is actually pretty vibrant. Especially in earths early years. If speciation takes billions of years of fairly stable conditions for mutations to be beneficial then this seems like a very long shot. And a shot that's been taken over and over again.
2. All the natural processes predict a bottom-up development of taxonomic hierarchy. Over time we should see a proliferation of species first then with a lot more time we should see a proliferation of genera etc. until one or more phyla finally appear.
However, the fossil record reveals the opposite. It reveals a top down hierarchy.
" As paleontologists Douglas Erwin, James Valentine, and John Sepkoski have observed with respect to the Avalon and Cambrian explosions, “The major pulse of diversification of phyla occurs before that of classes, classes before that of orders, and orders before that of families.”"
The most advanced phylum appears at the same time as the most primitive Cambrian phyla.
And they appear in the fossil record, coincidentally, (serendipitously?) at the same time the minimum level of oxygen they require is reached - 10% and not over millions of years but within a relatively short period of time at the beginning of the Cambrian not its middle or end. That's why they call it an explosion apparently. Both nonvertebrate chordates and vertebrates appear at that time.
Fifty animal phyla appeared at that time. Thirty exist on earth today. Of those 30, at least 28 were present during the Cambrian period and most of those at its beginning.
"paleontologists Kevin Peterson, Michael Dietrich, and Mark McPeek state in a review paper, “Elucidating the materialistic basis for the Cambrian explosion has become more elusive, not less, the more we know about the event itself.”"
Ref: Kevin J. Peterson, Michael R. Dietrich, and Mark A. McPeek, “MicroRNAs and Metazoan Macroevolution: Insights into Canalization, Complexity, and the Cambrian Explosion,”
BioEssays 31, no. 7 (July 2009): 737,
doi:10.1002/bies.200900033.
And apparently
"Nearly all paleontologists who have written reviews on the Cambrian explosion in the peer-reviewed scientific literature have made this concession."
Ref: Jeffrey S. Levinton, “The Cambrian Explosion: How Do We Use the Evidence?”
BioScience 58, no. 9 (October 2008): 855,
doi:10.1641/B580912; Gregory A. Wray, “Rates of Evolution in Developmental Processes,”
American Zoologist32, no. 1 (January–February, 1992): 131,
doi:10.1093/icb/32.1.123.
How do we explain these things evolutionarily.